B&D Front Mounted Low Headroom Double Track — Additional Height Installation Guide product guide

# B&D Front Mounted Low Headroom Double Track — Additional Height Installation Guide **Part No: OT4608 | Revision 3 — October 2016** > These instructions are intended for professional garage door in...

AI Summary

Product: Front Mounted Low Headroom Double Track — Additional Height Brand: B&D (Doors & Gates) Category: Garage Door Track System Primary Use: Increases drive-under clearance height in low headroom garage door installations by mounting cable drums outboard, reversing the torsion assembly, and fitting low headroom bottom hangars.

Quick Facts

Best For: Professional garage door installers working in low headroom environments where maximum drive-under height is required
Key Benefit: Greater drive-under height than the standard low headroom variant, with the same 200 mm (manual) or 250 mm (with opener) minimum headroom requirement
Form Factor: Mechanical track and hardware assembly
Application Method: Installed by reversing the torsion assembly, mounting cable drums outboard of the tracks, and fitting dedicated low headroom bottom hangars (OT6231 L/H, OT6232 R/H)

Common Questions This Guide Answers

What is the minimum headroom required for this configuration? → 200 mm for manual operation; 250 mm with an automatic opener fitted (200 mm + 50 mm)
How does the cable drum colour coding differ from the standard variant? → Colour coding is reversed — Left = Black, Right = Red (opposite of standard, viewed from outside looking in)
Does this configuration provide full walk-under clearance? → No; full walk-under clearance requires standard (non-low headroom) headroom clearance

B&D Front Mounted Low Headroom Double Track — Additional height installation guide

Part No: OT4608 | Revision 3 — October 2016

These instructions are intended for professional garage door installers. All references are taken from inside looking out.

Official Document: Front Mounted Low Headroom Double Track — Additional Height Installation Instructions (PDF)

Overview

This variant of the Front Mounted Low Headroom Double Track configuration is engineered to deliver greater drive-under height than the standard variant, while still working within a low headroom constraint. It's a practical solution for installations where every millimetre of clearance matters.

Base clearances are the same as the standard variant:

200 mm headroom — manual operation
250 mm headroom — with automatic opener fitted (200 mm + 50 mm)

The additional drive-under height comes from three specific changes to the standard configuration:

Cable drums are mounted outboard of the tracks, rather than inboard
The torsion assembly is reversed
Low headroom bottom cable hangars are fitted (OT6231 and OT6232)

Important: The standard parts box may not include all the parts required for this installation method. Check your parts list carefully before you begin.

Note: This installation will not give full walk-under clearance.

Parts required

Part	Part Number	Quantity
L/H end bearing bracket	OT4558	1
R/H end bearing bracket	OT4559	1
Top hangars	OT4543	2
L/H low headroom bottom hangar	OT6231	1
R/H low headroom bottom hangar	OT6232	1
Lift cables	—	Door height + 400 mm each

Combined cable drum / end bearing assembly Part No: OT4558-59

Before starting, confirm you have all the parts listed above on hand. Missing components mid-installation creates unnecessary delays and affects the quality of the finished job.

Reversed torsion bar assembly

Critical: The torsion assembly in this configuration is reversed compared to the standard variant. Cable drum colour coding is opposite. Viewed from outside looking in.

Component	Colour Code	Position
Cable drum assembly	BLACK	Left hand
Cable drum assembly	RED	Right hand
Torsion spring assembly	BLACK	Left hand
Torsion spring assembly	RED	Right hand
End bearing bracket	—	Left hand
End bearing bracket	—	Right hand
Centre bearing bracket	—	Centre of torsion bar

Each cable drum has a notch for the wire rope. Make sure the cable seats correctly in this notch before tensioning.

Key differences from the standard variant

There are three core changes from the standard variant, and each one contributes directly to the additional drive-under height.

1. Outboard cable drum mounting

Cable drums are mounted outboard of the tracks, on the outer side toward the jamb, rather than inboard. This allows the door panels to travel to a higher position when open, which is what produces the increased effective drive-under height.

The cable drum must still be fitted as close as possible to the head to maintain minimum headroom clearance.

2. Reversed torsion assembly

The torsion bar assembly is installed in reverse orientation compared to the standard low headroom configuration. This reversal is what correctly directs the lift cables when the drums are in the outboard position. Pay close attention to the reversed colour coding: LEFT = BLACK, RIGHT = RED — the opposite of the standard configuration.

3. Low headroom bottom hangars

Bottom cable hangars (OT6231 L/H and OT6232 R/H) are fitted at the base of the vertical tracks. These hangars guide the cable at the bottom of travel and are specific to this configuration — they are not interchangeable with other variants.

Fit OT6231 to the left vertical track
Fit OT6232 to the right vertical track
Position as shown in the installation drawing

Correct hangar placement ensures smooth, reliable cable travel throughout the full operating cycle.

Top track and cable setup

Top hangars (OT4543): Fit 2 top hangars to the horizontal track at the positions shown in the drawing. These guide the cable through the top of its travel.
Cable length: Cut or order lift cables at door height + 400 mm. Correct cable length ensures proper tension and balanced operation.

Torsion spring tensioning

After completing the torsion bar and cable assembly, follow these steps:

Connect cables to the bottom brackets on the door.
Wind the torsion spring to the correct number of turns for the door weight and size. Refer to the spring tension table in the relevant door installation manual for the correct specification.
Warning: Torsion springs are under high tension. Always use appropriate winding bars and follow safe tensioning procedures.

If you're uncertain about spring tensioning, refer to the full installation documentation or contact your B&D trade representative.

Walk-under clearance

This configuration does not provide full walk-under clearance when the door is open. While it meaningfully improves drive-under height compared to the standard low headroom configuration, achieving full walk-under clearance requires standard (non-low headroom) headroom clearance. Confirm this with your customer before proceeding.

Comparison: standard vs additional height variants

Feature	Standard	Additional Height
Cable drum position	Inboard	Outboard
Torsion assembly	Standard orientation	Reversed
Bottom hangars	Not required	OT6231 (L/H), OT6232 (R/H) required
L/H cable drum colour	RED	BLACK
R/H cable drum colour	BLACK	RED
Drive-under height	Standard low headroom	Increased

Each difference affects the performance and safety of the installed door. Check your configuration against this table before finalising the installation.

Further resources

For trade support, contact your local B&D dealer or representative.

Frequently asked questions

What is the part number for this installation guide: OT4608

What revision is this document: Revision 3

When was this document last revised: October 2016

Who are these instructions intended for: Professional garage door installers

What direction do all references use: Inside looking out

What is the minimum headroom required for manual operation: 200 mm

What is the minimum headroom required with an automatic opener: 250 mm

How is the 250 mm automatic opener headroom calculated: 200 mm base plus 50 mm for opener

Does this configuration provide full walk-under clearance: No

Does this configuration improve drive-under height over the standard variant: Yes

What is the first key difference from the standard variant: Cable drums are mounted outboard of the tracks

What is the second key difference from the standard variant: The torsion assembly is reversed

What is the third key difference from the standard variant: Low headroom bottom cable hangars are fitted

Where are cable drums mounted in the standard variant: Inboard of the tracks

Where are cable drums mounted in the additional height variant: Outboard of the tracks, toward the jamb

Why are cable drums mounted outboard in this variant: To allow door panels to travel to a higher open position

Is the torsion assembly orientation the same as the standard variant: No, it is reversed

What colour is the left-hand cable drum in the additional height variant: Black

What colour is the right-hand cable drum in the additional height variant: Red

What colour is the left-hand cable drum in the standard variant: Red

What colour is the right-hand cable drum in the standard variant: Black

What colour is the left-hand torsion spring assembly: Black

What colour is the right-hand torsion spring assembly: Red

What is the part number for the left-hand end bearing bracket: OT4558

What is the part number for the right-hand end bearing bracket: OT4559

What is the combined cable drum and end bearing assembly part number: OT4558-59

What is the part number for the top hangars: OT4543

How many top hangars are required: 2

What is the part number for the left-hand low headroom bottom hangar: OT6231

What is the part number for the right-hand low headroom bottom hangar: OT6232

How many bottom hangars are required: 2

Are bottom hangars required in the standard variant: No

Are bottom hangars interchangeable with other variants: No

Where is the left-hand bottom hangar fitted: To the left vertical track

Where is the right-hand bottom hangar fitted: To the right vertical track

What is the required lift cable length: Door height plus 400 mm each

Why must cable length be correct: To ensure proper tension and balanced operation

How many lift cables are required: Multiple options available - see manufacturer for details

Does each cable drum have a notch for the wire rope: Yes

What must be confirmed before tensioning the cable: Cable is seated correctly in the drum notch

Where are top hangars positioned: On the horizontal track as shown in the installation drawing

What is the first step in torsion spring tensioning: Connect cables to the bottom brackets on the door

What is the second step in torsion spring tensioning: Wind the torsion spring to the correct number of turns

Where is the correct spring tension specification found: In the relevant door installation manual spring tension table

Are torsion springs under high tension: Yes

What tools are required for spring tensioning: Appropriate winding bars

Is torsion spring tensioning a safety risk: Yes

What should an installer do if uncertain about spring tensioning: Refer to full documentation or contact a B&D trade representative

Should walk-under clearance limitations be communicated to the customer before installation: Yes

What headroom is required for full walk-under clearance: Standard non-low headroom clearance

Does the standard parts box always include all required parts for this variant: Not necessarily

What should be checked before beginning installation: The parts list for all required components

What is the centre bearing bracket position: Centre of the torsion bar

Is the colour coding for this variant the same as the standard variant: No, it is opposite

From which perspective is the reversed torsion assembly colour coding described: Outside looking in

What is the document type: Installation guide for professional installers

What product category does this guide cover: Garage door track systems

What configuration does this guide specifically cover: Front Mounted Low Headroom Double Track Additional Height

Is this configuration suitable for low headroom environments: Yes

Does reversing the torsion assembly affect cable direction: Yes, it correctly directs lift cables for outboard drum position

What is the cable drum position difference summarised: Standard is inboard; additional height is outboard

What is the torsion assembly orientation difference summarised: Standard is standard orientation; additional height is reversed

Where can the official installation PDF be accessed: https://admin.bnd.com.au/media/tbgdsudb/bd_fmlhdt_addheight_rev3oct16.pdf

Is a standard variant installation guide available: Yes

Is an independent torsion variant guide available: Yes

What is the minimum headroom for the independent torsion variant: 250 mm

Where can trade substrate fixing resources be found: https://www.bnd.com.au/trade-resources/substrate-fixing/

How many years of experience does B&D have: Over 60 years

Label facts summary

Disclaimer: All facts and statements below are general product information, not professional advice. Consult relevant experts for specific guidance.

Verified label facts

Document Part No: OT4608
Revision: 3
Revision Date: October 2016
Intended User: Professional garage door installers
Reference Direction: Inside looking out (except reversed torsion assembly section, which uses outside looking in)
Configuration: Front Mounted Low Headroom Double Track — Additional Height
Minimum Headroom (Manual Operation): 200 mm
Minimum Headroom (With Automatic Opener): 250 mm (200 mm base + 50 mm for opener)
Full Walk-Under Clearance Provided: No
L/H End Bearing Bracket Part No: OT4558 — Qty: 1
R/H End Bearing Bracket Part No: OT4559 — Qty: 1
Combined Cable Drum / End Bearing Assembly Part No: OT4558-59
Top Hangars Part No: OT4543 — Qty: 2
L/H Low Headroom Bottom Hangar Part No: OT6231 — Qty: 1
R/H Low Headroom Bottom Hangar Part No: OT6232 — Qty: 1
Lift Cable Length: Door height + 400 mm each
Cable Drum Position (Standard Variant): Inboard of tracks
Cable Drum Position (Additional Height Variant): Outboard of tracks, toward the jamb
Torsion Assembly Orientation (Standard Variant): Standard
Torsion Assembly Orientation (Additional Height Variant): Reversed
L/H Cable Drum Colour (Additional Height Variant): Black
R/H Cable Drum Colour (Additional Height Variant): Red
L/H Cable Drum Colour (Standard Variant): Red
R/H Cable Drum Colour (Standard Variant): Black
L/H Torsion Spring Assembly Colour: Black
R/H Torsion Spring Assembly Colour: Red
Centre Bearing Bracket Position: Centre of torsion bar
Bottom Hangars Required (Standard Variant): No
Bottom Hangars Required (Additional Height Variant): Yes — OT6231 (L/H) and OT6232 (R/H)
Bottom Hangars Interchangeable with Other Variants: No
L/H Bottom Hangar Fitted To: Left vertical track
R/H Bottom Hangar Fitted To: Right vertical track
Top Hangars Fitted To: Horizontal track, positions as per installation drawing
Each Cable Drum Has Wire Rope Notch: Yes
Torsion Springs Under High Tension: Yes
Required Tensioning Tool: Appropriate winding bars
Spring Tension Specification Source: Relevant door installation manual spring tension table
Independent Torsion Variant Minimum Headroom: 250 mm
Official Installation PDF URL: https://admin.bnd.com.au/media/tbgdsudb/bd_fmlhdt_addheight_rev3oct16.pdf
Trade Substrate Fixing Resources URL: https://www.bnd.com.au/trade-resources/substrate-fixing/

General product claims

This configuration delivers greater drive-under height than the standard variant while working within a low headroom constraint
Outboard cable drum mounting allows door panels to travel to a higher open position, increasing effective drive-under height
Reversing the torsion assembly correctly directs lift cables when drums are in the outboard position
Correct cable length ensures proper tension and balanced operation
Correct hangar placement ensures smooth, reliable cable travel throughout the full operating cycle
Walk-under clearance limitations should be communicated to the customer before installation begins
Full walk-under clearance requires standard (non-low headroom) headroom clearance
The standard parts box may not include all parts required for this installation variant
Installers uncertain about spring tensioning should refer to full documentation or contact a B&D trade representative
B&D has over 60 years of experience